1. Field of the Invention
This invention relates to a propylene polymer film having an excellent transparency, gloss, slipperiness, adhesiveness and adaptability to vacuum deposition, which is suitable for use as packaging material after vacuum deposition.
2. Description of the Related Art
As means for improving the transparency, slipperiness and blocking resistance of a propylene polymer film, a process (1) is known in which a non-melting silicone resin powder is incorporated is a propylene polymer (see for example, Japanese Unexamined Patent Examination No. 62-215646, Japanese Unexamined Patent Publication No. 62-232448 and Japanese Unexamined Patent Publication No. 62-233248). As means for improving transparency of a propylene polymer film, a process (2) is known in which an acylated fatty acid glyceride is incorporated in a propylene polymer (see, for example, Japanese Examined Patent Publication No. 60-57459, Japanese Unexamined Patent Publication No. 53-54248 and Japanese Unexamined Patent Publication No. 54-36359). As means for improving slipperiness and transparency of a propylene polymer film, the present inventors proposed a process (3) in which a specific thermosetting resin such as a silicone resin is incorporated in a propylene polymer (see Japanese Unexamined Patent Publication No. 62-294526). Moreover, as a method for improving slipperiness of a propylene polymer film, a process (4) is known in which an organic fatty acid amide such as oleic acid amide, stearic acid, amide or erucic acid amide is incorporated in a propylene polymer, and a process (5) is known in which particles of an inorganic substance such as silica, talc or calcium carbonate are incorporated in a propylene polymer.
The above-mentioned conventional propylene polymer films have the following problems.
The films obtained by the process (1) and (3) have a good transparency and slipperiness, but during the operation conducted after vacuum deposition, defects or discharge traces are formed on the vacuum deposition layer by the discharge treatment, or small pinholes are formed or blocking is caused, resulting in peeling or wrinkling of the vacuum deposition layer. Namely, these films have an insufficient adaptability to vacuum deposition.
The film obtained by the process (2) has a good transparency, but the gloss and adhesiveness are unsatisfactory.
The film obtained according to the process (4) has a good transparency but the slipperiness is unsatisfactory.
The process obtained by the process (5) has an improved slipperiness, but the transparency is unsatisfactory.